In the delivery of a prosthesis in a minimally invasive manner, use is made of a working cannula which is inserted through an incision in a patient's skin to the site to facilitate percutaneous delivery of the prosthesis to the site. A delivery mechanism is inserted into a lumen of the cannula for delivery of the prosthesis to the site. Generally, the cannula and the delivery mechanism are mounted on some form of structure such as a control device, a dispensing arrangement, or the like, For example, the cannula which helps dock the delivery system to the patient, in turn, can be docked to another fixed structure like the operating table using clamps so as to free the hands of the operator and to also provide stability while performing the device delivery. In addition, the cannula and the delivery mechanism are made as thin as possible so that the incision is made as small as possible.
In the case of a tissue prosthesis such as an intervertebral disc nucleus prosthesis, there is a need to perform an annulotomy on the annulus of the disc to gain access to an interior of the disc. The working cannula, after being inserted percutaneously, needs to be aligned with the opening formed in the annulus and retained in such alignment. It would therefore be advantageous to disturb the position of the cannula and the delivery device as little as possible and to keep the assembly as stable as possible,